Extreme surface and near-bottom currents in the northwest Atlantic
This study presents a methodology for estimating extreme current speeds fromnumerical model results using extremal analysis techniques. This method is used to estimate theextreme near-surface and near-bottom current speeds of the northwest Atlantic Ocean with50-year return periods from 17 years of m...
Published in: | Natural Hazards |
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Main Authors: | , , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
Springer
2012
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Subjects: | |
Online Access: | https://doi.org/10.1007/s11069-012-0303-5 http://ecite.utas.edu.au/82914 |
Summary: | This study presents a methodology for estimating extreme current speeds fromnumerical model results using extremal analysis techniques. This method is used to estimate theextreme near-surface and near-bottom current speeds of the northwest Atlantic Ocean with50-year return periods from 17 years of model output.The non-tidal currents produced by a threedimensionalocean circulation model for the 19882004 period were first used to estimate andmap the 17-year return period extreme current speeds at the surface and near the bottom. Extremalanalysis techniques (i.e., fitting the annualmaxima to the Type I probability distribution) are usedto estimate and map the 50-year extreme current speeds. Tidal currents are dominant in someparts of the northwest Atlantic, and a Monte Carlo-based methodology is developed to take intoaccount the fact that large non-tidal extrema may occur at different tidal phases. The inclusion oftidal currents in this way modifies the estimated 50-year extreme current speeds, and this isillustrated along several representative transects and depth profiles. Seasonal variations areexamined by calculating the extreme current speeds for fall-winter and springsummer. Finally,the distribution of extreme currents is interpreted taking into account (1) variability about thetime-mean current speeds, (2) wind-driven Ekman currents, and (3) flow along isobaths. |
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